Increasing the base number of calcium petroleum sulfonate



May 16, 1967 w. N. AXE ETAL INCREASING THE BASE NUMBER OF CALCIUM PETROLEUM SULFONATE Filed May 22, 1964 ON LL L TTOR/VEVS nited States Patent 3,320,162 INCREASHNG THE EASE NUMBER F CALCIUM PETRULEUM SULFONATE William N. Axe and Sidney Schi, Bartlesville, Okla., as-

signors to Phillips Petroleum Company, a corporation of Delaware Filed May 22, 1964, Ser. No. 369,376 4 Claims. (Cl. 252-33) This invention relates to increasing the base number of a calcium petroleum sulfonate. In one aspect, the invention relates to a process for increasing the base number of a calcium sulfonate of a high viscosity paraii'inic petroleum lubricating stock by contacting with methanol, either calcium oxide or calcium hydroxide, and one or more of ammonium carbonate, ammonium acid carbonate or arnmonium carbamate. In another aspect, this invention relates to an improved lubricant additive comprising an overbased calcium petroleum sulfonate produced by the process of this invention. ln another aspect this invention relates to an improved lubricant `containing the novel lubricant additive of this invention.

Calcium petroleum sulfonates are widely used in the manufacture of additives for lubricating oil used in combustion engines. These materials impart detergency to the lubricating oils and thus assist in keeping the internal engine parts clean and -reducing sludge formation in the oils. By increasing the alkaline reserve of the additive (overbasing the additive), equivalent detergency is obtained with a lower concentration of additive in the lubricating oil. Also, higher alkaline reserve neutralizes larger quantities of acidic combustion products which accumulate in the oil.

A recently developed detergent additive is produced by the novel process described in copending application Ser. No. 222,357, Whitney et al., tiled Sept. 10, 1962, now U.S. Patent No. 3, 135,693. This additive, which comprises a calcium petroleum sul-fonate, not only gives excellent results in increasing the detergency of lubricating oils and reducing sludge formation, but also has quite adequate alkaline reserve for many applications. HOW- ever, for some uses, for example, under conditions such that large quantities of acid are formed, as in diesel engines burning high sulfur fuels, it is desirable to increase the alkaline reserve of this detergent additive. Many previously known processes for overbasing -lubricant oil additives, specifically those processes for overbasing metal sulfonates of mahogany acids, have not proved to be applicable to the Whitney et al. developed additives.

It is an object of this invention to increase the base number of a calcium petroleum sulfouate.

Another object of this invention is to provide novel overbased calcium petroleum sulfonates.

Another object of this invention is to provide improved lubricants containing novel overbased calcium petroleum sulfonates.

Other aspects, objects and the advantages of our invention are apparent in the written description, the drawing and the claims.

Alkaline reserve can be measured by base number, which is the number of milligrams of potassium hydroxide equivalent to` the amount of acid required to neutralize thealkaline constituents present in a one-gram sample. A compound having a base number higher than can be obtained from the calcium petroleum sulfonate alone is said to befoverbased, sometimes superbasicf In this application the reported base numbers are obtained by the method described in Analytical Chemistry, volume 23, page 337 (1951), and volume 24, page 519 (1952).

Petroleum sulfonic acid which is neutralized to form petroleum sulfonates normally includes appreciable amounts of various hydrocarbons not having the acid ice group so that when the sulfonate is formed, the resulting product is a mixture of hydrocarbons and petrole-um sulfonates. When the sulfonic acid is neutralized with au excess of calcium oxide or calcium hydroxide to form the sulfonate, the resulting product has a relatively small alkaline reserve. Addition of a large excess of neutralizing material normally does not materially increase the alkaline reserve beyond this point, since the excess material is removed, for example, by ltration, prior to the use of the sulfonate in a lubricant.

According to our invention, the alkaline reserve of the `additives of U.S. Patent No. 3,135,693 is increased by contacting with methanol, a compound selected from the group consisting of calcium oxide and calcium hydroxide, and a compound selected from the group consisting of ammonium carbonate, ammonium acid carbonate (ammonium bicarbonate) and ammonium carbamate, followed by heating the resulting mixture to a suitable temperature for sufficient time to overbase the composition. The amount of the methanol usually is in the range of 5 to 100 volume percent of the lubricant additive composition which is overbased. By lubricant additive compositions is meant either an undiluted calcium petroleum sulfonate or a mixture of calcium petroleum sulfonate with unsulfonated oils, either oils present when the sulfonate is produced or an oil added later.

The amount of uncombined water in the mixture must be severely limited for successful operation of our invention. Preferably the amount of water is not more than about 5 volume percent of the amount of methanol present and in any event should not exceed about 7 volume percent of the methanol.

The amount of calcium oxide or hydroxide to be used depends upon the amount of overbasing to be effected. The calcium compound usually is added in an amount equal to 2 to 6 times the amount chemically equivalent to the desired overbasing.

A complex equilibrium exists among ammonium carbonate, ammonium bicarbonate and ammonium carbamate. All of these compounds tend to break down to ammonia and carbon dioxide, although ammonium carbamate needs Water to accomplish this. When using ammonium carbamate, the needed water can be added as water vapor in the stripping gas or as chemically combined water by use of calcium hydroxide. At least a suliicient amount of the ammonium compound is used to furnish sufficient carbon dioxide by decomposition to react with all of the calcium compound.

Preferably a stripping gas is passed through the mixture during the heating step, the gas being one which is non-reactive under the conditions of the heating step. Suitable gases include natural gas, nitrogen, etc. The heating step normally is accomplished at a temperature in the range of 150 to 350 F., preferably 200 to 300 F., until basic vapors no longer are evolved, usually 1/2 to 48 hours. However, higher temperatures can be used if v desired, the upper limit usually being determined by cracking of the petroleum sultonate material. A ternperatu-re of 500 F. normally will avoid substantially all cracking, but temperatures up to about 600 F. can be used without appreciable cracking. The stripping gas effects mixing and removes the basic vapors from the liquid phase more quickly. The gas stripping is not essential to accomplish overbasing, but shortens the reaction time at a given temperature.

After the reaction is complete, solids are removed from the reaction mixture, yfor example, by ltering or centrifuging, and the additive then is ready for use in blending of the lubricating oils.

In producing the sulfonated petroleum material of this invention, the base stock is selected from highly parainic,

deasphalted and solvent refined petroleum fractions hav- 'ing a viscosity of about 180 to 230 SUS at 210 F. and having a viscosity index of at least about 85. A preferred material is a propane-fractionated, solvent-extracted and dewaxed Mid-Continent oil of about 200 to 215 SUS at 210 F. and having a -viscosity index of about 85 to 100 or higher. The residual material from the propane fractionation contains the rejected asphalt and aromatic oils. Following the propane fractionation step, the overhead oil fraction is solvent extracted to remove additional aromatic hydrocarbons.

A Mid-Continent oil is more precisely defined as a mixed base or intermediate base oil. The base of a crude petroleum is descriptive of the chemical nature of its main constituents. A petroleum can be described as parafiin base, asphalt base or mixed base (intermediate base), accordingly, as parafiin wax, asphalt, or both parafiin Wax and asphalt are present in the residue after distillation of the lighter components. In this application, Mid-Continent oil and intermediate base oil are used interchangeably.

These oils are contacted with sulfonating agents such as fuming sulfuric acid, chlorosulfonic acid, and sulfur trioxide, a particularly preferred sulfonating agent being a solution of sulfur trioxide in liquid sulfur dioxide. The petroleum stocks are contacted with the sulfonating agents at temperatures of from 50 to 200 F., preferably from 8O to 150 F., for about l to 90 minutes. The ratio of sulfonating agent to oil can vary considerably, but generally is within the range of from about 0.1:1 to 1:1 on a weight basis, the sulfonating agent being calculated as 20 percent fuming sulfuric acid.

The efiiuent from the sulfonation step is a petroleum sulfonic acid and this material is converted to an overbased calcium petroleum sulfonate by the method of this invention.

In the embodiment illustrated in the drawing, a selected petroleum stock is introduced to sulfonation zone 10 through conduit 11. A sulfonating agent such as sulfur trioxide dissolved in sulfur dioxide is introduced to sulfonation zone 10 through -conduit 12. The reaction products are transported through conduit 13 to flash zone 14, where sulfur dioxide is removed through conduit 15. The remaining reaction product passes through conduit 16 to neutralization zone 17 where it is diluted with a hydrocarbon solvent, such as naphtha, introduced through conduit 18, and is neutralized by a slurry of metal hydroxide, such as an aqueous slurry of lime, introduced through conduit 19. The resulting substantially neutralized slurry of calcium sulfate and calcium hydroxide in Water and of diluted sulfonation reaction effluent is passed through conduit 20 to stabilization zone 21, where the reaction product is maintained in the presence of the metal hydroxide at elevated temperature and elevated pressure so that the base number of the sulfonate is raised as high as possible by this action. The stabilized material then proceeds through conduit 22 into drying zone 23 in which step substantially all of the water is removed through conduit 24. The stabilized and dehydrated reaction product is passed through conduit 26.

In a preferred process, filtration zone 27 is eliminated and this is illustrated in the drawing by the inclusion of conduit 44 having a valve 44A therein. Conduit 44 connects conduit 26 with conduit 29, thus by-passing the filtration zone 27. In this manner, excess lime present in the efiiuent from drying zone 23 is retained whereby the amount of lime introduced through conduit 31 can be reduced or, in some cases, eliminated entirely.

When it is desired to include .a filtration step at this point, the product is passed throughconduit 26 to filtration zone 27, valve 44A being closed and valve 45 being open. It is desirable in most instances to add a solvent such as naphtha to conduit 26 to facilitate the filtration step. A solids containing stream is removed through conduit 28 While the filtrate comprising a metal petroleum sulfonate continues through conduit 29 into mixing zone 30 wherein any needed lime is added through conduit 31, along with methanol in conduit 32 and the ammonium compound in conduit 33. The mixture then passes through conduit 34 into heating zone 36 from which vapor is removed through conduit 38. Preferably, a non-reactive gas is passed through the heating zone as through conduit 37. The overbased material then is passed through conduit 39 to filtration zone 41 from which a solids containing stream is removed through conduit 42 While the product continues for further treatment through conduit 43.

Example Twenty parts of calcium petroleum sulfonate lubricating oil additive comprising 50 percent calcium petroleum sulfonate of a propane-fractionated, phenol-extracted and dewaxed Mid-Continent lubricating oil fraction of about 203 SUS viscosity at 210 F. and a viscosity index of about 93, made in accordance with the above description, was diluted with an equal weight of SAE 10 refined lubricating oil and mixed with 20 parts by weight of methanol, 1l parts by weight of calcium hydroxide and 15 parts by weight of ammonium carbonate. The mixture was heated to 250 F. and maintained at this temperature for 7 hours. Natural gas was bubbled through the mixture during the period of heating. At the end of the heating period, basic vapors no longer were evolved. The reaction mixture was cooled, diluted with benzene, centrifuged for one hour, the liquid decanted from `the separated solid, and the benzene diluent stripped from the liquid. The product had a base number of 93 MgKOH/ g., or a base number of 186 based on the original amount of additive. The base number of the additive before treatment (free ofSAE 10y diluent) was about 7.5 MgKOH/ g.

Reasonable variation and modification are possible within the scope of our invention which sets forth novel lubricants and lubricant additives and a process for producing the overbase calcium petroleum sulfonates from high viscosity paratlinic petroleum lubricating stock.

We claim:

1. A process for producing a lubricant additive which comprises the steps of:

contacting a lubricant additive composition comprising a compound selected from the group consisting of a petroleum sulfonic acid and a calcium petroleum sulfonate, wherein the sulfonated stock is highly parafiinic, deasphalted and solvent refined petroleum fraction having a viscosity of about 180 to 230 SUS at 210 F. and having a viscosity index of at least about 85, with methanol, in an amount equal to 5 to volume percent of said composition, an amount of a calcium compound selected from the group consisting of calcium oxide, and calcium hydroxide to provide 2 to 6 times the amount chemically equivalent to a desired overbasing, and va sufficient amount of an ammonium compound selected from the group consisting of ammonium carbonate, ammonium bicarbonate and ammonium carbamate to furnish carbon dioxide lby decomposition =to react with all of said calcium compound, while maintaining the uncombined water content of the resulting mixture below about 7 volume percent of the amount of said methanol; and

heating to a temperature in the range of `to 500 F.

until basic vapors no longer are evolved.

2. A lubricant additive prepared by the steps of:

contacting a lubricant additive composition comprising a compound selected from the group consisting of a petroleum sulfonic acid and a calcium petroleum sulfonate, wherein :the sulfonated stock is highly parainic, deasphalted and solvent refined petroleum fraction having a viscosity of about to 230 SUS zat 210 F. and having a viscosity index of at least .about 85, with methanol, in an amount equal to 5 to 100 volume percentof saidcomposition, an amount of a calcium compound selected from the group consisting of calcium oxide, and calcium hydroxide to provide 2 -to 6 times the amount chemically equivalent to a desired overbasing,

contacting a lubricant additive composition comprising a compound selected from `the group consisting of a petroleum sulfonic acid and a calcium petroleum sulfonate, wherein the sulfonated stock is highly and a suicient amount of an ammonium com- 5 parainic, deasphalted and solvent refined petroleum pound selected from the group consisting of amfraction having a viscosity of about 180 to 230 SUS monium carbonate, ammonium bicarbonate and amat 210 F. and having a viscosity index of at least monium carbamate to furnish carbon dioxide by deabout 85, with methanol, in an amount equal to composition to react With all of said calcium com- 5 to 100 volume percent of said composition, an pound, while maintaining the uncombined water con- 10 amount of a calcium compound selected from the tent of the resulting mixture below about 7 volume percent ofthe amount of said methanol; and

group consisting of calcium oxide, and calcium hydroxide to provide 2 to 6 times the amount chemically heating to a temperature in the range of 150 to 500 F. equivalent to a desired overbasing, and a sucient until basic vapors no longer as evolved. amount of an ammonium compound selected from 3. A process for producing a lubricant additive which l5 the group consisting of ammonium carbonate, amcomprises the steps of: monium bicarbonate and ammonium carbamate to contacting a lubricant additive composition comprising furnish carbon dioxide 'by decomposition to react with all of said calcium compound, while maintaining the uncombined Water content of the resulting mixture below about 7 volume percent of the amount of said methanol; and

heating to a temperature in the range of 150 to 500 F.

until basic vapors no longer are evolved while passing a non-reactive gas through the mixture -to effect to 100 volume percent of said composition, lan 25 mixing and assist in removing said basic vapors. amount of a calcium compound selected from the group consisting of calcium oxide, and calcium hydroxide to provide 2 to 6 times the amount chemically equivalent to a desired overbasing, and a sufli- References Cited by the Examiner UNITED STATES PATENTS 2,595,556 5/1952 Worth et al. cient amount of an ammonium compound selected 2 861951 11/1958 Cnrl le 252 33 from the group consisting of ammonium carbonate, 2865956 12/1958 Eisyet a-l ammonium 'bicarbonate and ammonium carbamate 2865957 12/1958 LO an 252 33 X to furnish carbon dioxide by decomposition to react 3223630 12/1965 G g 2g 33 with all of said calcium compound, while maintainragson ing the uncombined water content of the resulting FOREIGN PATENTS mixture below about 5 volume percent ofthe amount 212,323 10i/1956 Australm 0f Sald methanol; and 774,683 5/1957 Great Britain.

heating to a temperature in the range of 200 to 300 F. for 1/2 to 48 hours until basic vapors no longer are evolved.

4. A process for producing `a lubricant additive which comprises the steps of;

DANIEL E. WYMAN, Primary Examiner, 40 P. P. GARVIN, Assistant Examiner', 

1. A PROCESS FOR JPRODUCING A LUBRICANT ADDITIVE WHICH COMPRISES THE STEPS OF: CONTACTING A LUBRICANT ADDITIVE COMPOSITION COMPRISING A COMPOUND SELECTED FROM THE GROUP CONSISTING OF A PETROLEUM SULFONIC ACID AND A CALCIUM PETROLEUM SULFONATE, WHEREIN THE SULFONATED STOCK IS HIGHLY PARAFFINIC, DEASPHALTED AND SOLVENT REFINED PETROLEUM FRACTION HAVING A VISCOSITY OF ABOUT 180 TO 230 SUS AT 210*F. AND HAVING A VISCOSITY INDEX OF AT LEAST ABOUT 85, WITH METHANOL, IN AN AMOUNT EQUAL TO 5 TO 100 VOLUME PERCENT JOF SAID COMPOSITION, AN AMOUNT OF A CALCIUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF CALCIUM OXIDE, AND CALCIUM HYDROXIDE TO PROVIDE 2 TO 6 TIMES THE AMOUNT CHEMICALLY EQUIVALENT TO A DESIRED OVERBASING, AND A SUFFICIENT AMOUNT OF AN AMMONIUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMMONIUM CARBONATE, AMMONIUM BICARBONATE AND AMMONIUM CARBAMATE TO FURNISH CARBON DIOXIDE BY DECOMPOSITION TO REACT WITH ALL OF SAID CALCIUM COMPOUND, WHILE MAINTAINING THE UNCOMBINED WATER CONTENT OF THE RESULTING MIXTURE BELOW ABOUT 7 VOLUME JPERCENT OF THE AMOUNT OF SAID METHANOL; AND HEATING TO A TEMPERATURE IN THE RANGE OF 150 TO 500*F. UNTIL BASIC VAPORS NO LONGER ARE EVOLVED 